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tcp: move tcp_rack_advance() to tcp_input.c

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tcp_rack_advance() is called from tcp_ack() and tcp_sacktag_one().

Moving it to tcp_input.c allows the compiler to inline it and save
both space and cpu cycles in TCP fast path.

$ scripts/bloat-o-meter -t vmlinux.1 vmlinux.2
add/remove: 0/2 grow/shrink: 1/1 up/down: 98/-132 (-34)
Function                                     old     new   delta
tcp_ack                                     5741    5839     +98
tcp_sacktag_one                              407     395     -12
__pfx_tcp_rack_advance                        16       -     -16
tcp_rack_advance                             104       -    -104
Total: Before=22572680, After=22572646, chg -0.00%

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260127032147.3498272-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet
2026-01-27 03:21:47 +00:00
committed by Jakub Kicinski
parent 629a68865a
commit d5fb143dbe
3 changed files with 32 additions and 34 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
include/net/tcp.h
View File

@@ -2514,8 +2514,6 @@ void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced);
extern s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb,
u32 reo_wnd);
extern bool tcp_rack_mark_lost(struct sock *sk);
extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
u64 xmit_time);
extern void tcp_rack_reo_timeout(struct sock *sk);
/* tcp_plb.c */

32
net/ipv4/tcp_input.c
View File

@@ -1558,6 +1558,38 @@ static int tcp_match_skb_to_sack(struct sock *sk, struct sk_buff *skb,
return in_sack;
}
/* Record the most recently (re)sent time among the (s)acked packets
* This is "Step 3: Advance RACK.xmit_time and update RACK.RTT" from
* draft-cheng-tcpm-rack-00.txt
*/
static void tcp_rack_advance(struct tcp_sock *tp, u8 sacked,
u32 end_seq, u64 xmit_time)
{
u32 rtt_us;
rtt_us = tcp_stamp_us_delta(tp->tcp_mstamp, xmit_time);
if (rtt_us < tcp_min_rtt(tp) && (sacked & TCPCB_RETRANS)) {
/* If the sacked packet was retransmitted, it's ambiguous
* whether the retransmission or the original (or the prior
* retransmission) was sacked.
*
* If the original is lost, there is no ambiguity. Otherwise
* we assume the original can be delayed up to aRTT + min_rtt.
* the aRTT term is bounded by the fast recovery or timeout,
* so it's at least one RTT (i.e., retransmission is at least
* an RTT later).
*/
return;
}
tp->rack.advanced = 1;
tp->rack.rtt_us = rtt_us;
if (tcp_skb_sent_after(xmit_time, tp->rack.mstamp,
end_seq, tp->rack.end_seq)) {
tp->rack.mstamp = xmit_time;
tp->rack.end_seq = end_seq;
}
}
/* Mark the given newly-SACKed range as such, adjusting counters and hints. */
static u8 tcp_sacktag_one(struct sock *sk,
struct tcp_sacktag_state *state, u8 sacked,

32
net/ipv4/tcp_recovery.c
View File

@@ -111,38 +111,6 @@ bool tcp_rack_mark_lost(struct sock *sk)
return !!timeout;
}
/* Record the most recently (re)sent time among the (s)acked packets
* This is "Step 3: Advance RACK.xmit_time and update RACK.RTT" from
* draft-cheng-tcpm-rack-00.txt
*/
void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
u64 xmit_time)
{
u32 rtt_us;
rtt_us = tcp_stamp_us_delta(tp->tcp_mstamp, xmit_time);
if (rtt_us < tcp_min_rtt(tp) && (sacked & TCPCB_RETRANS)) {
/* If the sacked packet was retransmitted, it's ambiguous
* whether the retransmission or the original (or the prior
* retransmission) was sacked.
*
* If the original is lost, there is no ambiguity. Otherwise
* we assume the original can be delayed up to aRTT + min_rtt.
* the aRTT term is bounded by the fast recovery or timeout,
* so it's at least one RTT (i.e., retransmission is at least
* an RTT later).
*/
return;
}
tp->rack.advanced = 1;
tp->rack.rtt_us = rtt_us;
if (tcp_skb_sent_after(xmit_time, tp->rack.mstamp,
end_seq, tp->rack.end_seq)) {
tp->rack.mstamp = xmit_time;
tp->rack.end_seq = end_seq;
}
}
/* We have waited long enough to accommodate reordering. Mark the expired
* packets lost and retransmit them.
*/